1. Field of the Invention
This invention relates generally to mechanical locks for holding overlapping flaps of a wrap-around carton in place. More particularly, it is a single lock without a xe2x80x9cbackupxe2x80x9d locking system. The female lock has a unique locking ledge on an S-shaped cut line.
2. Prior Art
When fabricating a carton from a paperboard blank, opposite ends of the blank are conventionally attached to each other by glue or by a mechanical lock to form the bottom panel of the carton. In the case of a wrap-around carton, flaps located on the ends of the blank typically are overlapped and engaged with one another by mechanical locks formed in the flaps to form the bottom panel of the carton. Since the bottom panel must maintain its integrity throughout the use of the carton, it is essential that the locking system be capable of supporting the weight of the packaged articles, and remain engaged during shipping and handling of the constructed carton.
One approach to provide a stable mechanical lock assembly utilizes both primary and secondary locks. An example of such locking system is disclosed in U.S. Pat. No. 5,443,203 to Sutherland.
While the combination of a primary and secondary locking system may add to the security of a package, it is also somewhat redundant, like wearing both a belt and suspenders. It would be advantageous to provide a single lock locking system that is secure for a number of reasons. In the first place, a single lock locking system will enable less paperboard to be used in constructing a carton. Secondly, it is less complex to mechanically lock a single lock locking system than where you have both primary and secondary locks. With some types of small containers there is not a lot of room on the bottom panels of the carton to include a primary lock along with a secondary lock. Furthermore, the added security of having both the primary and secondary locking system may not be needed with containers that are light, such as yogurt and butter tubs.
Is an object of the present invention to provide a single lock locking system for locking wrap-around cartons. It is the further object of this invention to provide a carton locking system that allows a reduction in the amount of paperboard required to construct the carton. A further object of this invention is to provide a single lock locking system that can be utilized to package small containers in a wrap-around carton.
Briefly described, in its preferred form, the objects of this invention are achieved by providing a single lock locking system. An important feature of this system is the introduction of a locking ledge on a S-shaped cut line in the female lock. A locking shoulder of the male lock which projects from an end of the carton rests on this locking ledge.
These and other objects, features, and advantages of the present invention will become more apparent upon reading the following specification in conjunction with the accompanying drawing figures.